Improving anode cover material quality at Nordural - Quality tools and measures

Abstract

Anode cover material (ACM) composition and granulometry determines the properties of the anode cover. This paper describes the experience Nordural has had with a new ACM mixing station employing autogeneous milling and pressure vessel conveying of the material to the potrooms. The pros and cons of this system for delivering the required granulometry is discussed by showing the evolution of the ACM granulometry before and after the commissioning of the new mixing station. To evaluate the effect of the conveying system the granulometry of the material at the output of the mixing station is compared with the granulometry of the material on the anodes. The automated XRD/XRF method for bath analysis has also been used for evaluating the alumina- and chiolite composition of the ACM which can impact the bath mass balance and structural stability. Finally, heat flux data is shown as one measure of quality.